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EMBRYOLOGY AND DEVELOPMENT OF THE ENDOSPERM HAUSTORIUM OF ARCEUTHOBIUM DOUGLASII
Author(s) -
Jones B. L.,
Gordon C. C.
Publication year - 1965
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1965.tb06767.x
Subject(s) - endosperm , biology , zygote , haustorium , botany , megaspore , embryo , human fertilization , ovule , microbiology and biotechnology , anatomy , embryogenesis , genetics , host (biology)
Arceuthobium douglasii develops a dome‐like structure, the ovarian papilla, in which 2 megasporocytes are formed. The papilla is not a true ovule, for no integuments are formed, and it is forced aside by the developing endosperm. Megasporocytes are differentiated in the spring, but meiosis does not occur until the following spring. A tetrasporic embryo sac is developed which is 8‐nucleate at maturity. Pollination and fertilization occur approximately 13–14 months after initiation of the inflorescence. Only 1 of the 2 embryos develops after fertilization. After fertilization, the embryo sac segregates into 2 parts, one containing the zygote and the disintegrating synergids, the other the primary endosperm nucleus and the degenerating antipodals. This primary endosperm cell elongates toward the base of the ovarian papilla. Cytokinesis then forms an endosperm cell, adjacent to the zygote, and a haustorial cell. The haustorial cell forms several tiers of cells which persist during the development of the embryo and endosperm. The zygote, while still contained within the ovarian papilla, divides, forming a 2‐celled sphere. It remains unchanged until after it is conveyed out of the ovarian papilla by the developing endosperm. The development of the embryo and endosperm is arrested in the autumn approximately 3 months after their initiation. They complete their development the following spring and summer.